At the present time, systems having LEDs, converters and optics are jointly disposed in a housing, which is also called a package, by means of so-called molding processes. In a familiar method, the package is constructed directly from the individual components, which are then solidly joined to one another. In general, silicone resins are used for this purpose. Such a system is described, for example, in document DE 10 2005 009 066 A1.
A disadvantage of such a system, which is based on its essentially organic properties, is its low temperature resistance, which in general only attains a value of approximately 100° C. Based on the low temperature resistance, such a system is compatible with soldering processes only under certain conditions, since conducting such processes will bring about or require a high evolution of heat. In particular, the materials used in the prior art cannot be exploited further if the so-called junction temperature used in an LED chip at the present time increases from the current maximum of 100-150° C. to 200° C.
Also, such a system is not resistant to UV. Further, such a package is also not hermetically sealed and is thus susceptible to environmental influences, such as moisture. The increasing complexity of semiconductor components and different applications, however, requires a hermetic package. Examples of this are an LD and a photodetector or an LED with color monitor.
Another disadvantage of the known systems is based on the fact that they are not resistant to aging. In particular, the so-called degassing effects of plastics lead to an aging of the semiconductor chip. The preferably low wavelength of the emitted light in the case of the currently used materials leads to a degradation of the optical properties and of the adhesion mechanisms. In addition, a low heat conductivity of the plastics used, which particularly lies in a range of <1 W/mK is also a disadvantage.
The individual components are generally solidly joined to one another and provided in a package. A flexible matching, particularly of the index of refraction of the individual components to one another and to the wavelength of the light, is also only very difficult or generally not possible. Another disadvantage is the increased expenditure in manufacture, since the individual components must be assembled.